Scheduling and planning manufacturing operations are most desirably done in such manner as to meet required completion dates while simultaneously optimizing throughput and minimizing manufacturing costs. Computers operating under the control of conventional programming have been utilized advantageously to develop optimal manufacturing (also known as production) schedules for many production processes. However, in some systems, particularly those in which a number of discrete parts are manufactured simultaneously in a single operation, the production requirements create combinatorial optimization problems which require an impractical amount of computer time to solve. Additionally, certain production operations require repetitive and variable processing of manufactured parts (in other words, are dynamic in nature). In these instances, conventional programming is incapable of developing production schedules because most of the scheduling actions are non-quantifiable heuristics.
Expert systems, a class of so-called artificial intelligence imbued computer systems in which the analytical skills of an expert are set forth as rules dependent upon and applied against the expert's domain of knowledge (the "knowledge base") are capable of finding solutions to such problems. Several different rule-based expert system paradigms have been utilized in production scheduling and planning. Logic programming has been shown to be applicable in production planning in the paper by W. I. Bullers, S. Y. Nof and A. B. Whinston entitled "Artificial Intelligence in Manufacturing Planning and Control," AIIE Transactions, December 1980, pp 351-363. Similarly, a job shop scheduling system may be based on a schema representation paradigm as disclosed in the paper by M. S. Fox, et. al., entitled "ISIS: A Constraint Directed Reasoning Approach to Job Shop Scheduling," Intelligent Systems Laboratory, The Robotics Institute, Carnegie Mellon University Technical Report, Jun. 21, 1983, pp 83-88. Advantages of using a rule-based system for scheduling production in a so-called flexible manufacturing system have been described in the article by G. Bruno, A. Elia, and P. Laface entitled " A Rule-Based System to Schedule Production," Computer, July 1986, pp 32-40.
Heretofore, to our knowledge, no one has developed the heuristics and knowledge base necessary to produce a complete rule-based expert system capable of scheduling a multiple-pass batch production process, such as the glassing and furnacing operation for manufacture of glass-lined vessels used in chemical manufacturing. Such an expert system must account for numerous constraints including, but not limited to, availability and capacity of the furnace, availability of firing tools, allowed part mix, firing temperature and allowed differences in the thickness of the parts. Such an expert system must also provide the best solution to meeting delivery date requirements, optimizing furnace utilization and minimizing energy consumption. Furthermore, the solution should preferably be optimized for a plurality of furnaces that may operate simultaneously.